Keyboard with code output



April 15, 1969 B. HOWARD ET AL KEYBOARD WITH com: OUTPUT Sheet Filed July 20, 1966 INVENTORS WH 3 AC Y W M 0m R H 0 D W R Mm m R L April 15, 1969 B, HOWARD ET AL KEYBOARD WITH CODE OUTPUT II D r S H N w I T 4 R MC 0 5 o OWS E QAN T R N O f l NHm M 0 N5 w. Maw W H 2 QNN OW DUHHH I II I] l\\ m A U DO NP \sm 0 0 RL 0 D 00 EA M D O WOW 00 BR e 0 000000 0 h 0000 00 00 m. S 0000 00 000W w III!) 0 0 J M DM i llfinfu o n m Mm on Filed July 20, 1966 April 15, 1969 HOWARD ET AL KEYBOARD WITH CODE OUTPUT Sheet 3 of filed July 20, 1966 I22 I20 H6 INVENTORS BERNARD HOWARD ATTORNEYS April 15, 1969 B. HOWARD ET AL 3,439,] 18

KEYBOARD WITH CODE OUTPUT Filed July 20, 1966 Sheet 4 of 5 FIG.|O r

INVENTORS BERNARD HOWARD RALPH M. HIRSCH BY 62 M ATTORNEYS April 15, 1969 B HOWARD ET AL 3,439,118

KEYBOARD WITH CODE OUTPUT Filed July 20, 1966 Sheet 5 of 5 INVENTORS BERNARD HOWARD RALPH M. HIRSCH WQMH'M KI'TORNEYS United States Patent 3,439,118 KEYBOARD WITH CODE OUTPUT Bernard Howard, New Haven, and Ralph M. Hirsch, Woodbridge, Conn., assignors to Mite Corporation, New Haven, Conn., a corporation of Delaware Filed July 20, 1966, Ser. No. 566,523 Int. Cl. H041 15/12; B413 /00 US. Cl. 178-17 18 Claims This invention relates to keyboards, and more particularly to a keyboard which provides a code output on multiple conductors.

The general object of the invention is to provide an improved keyboard, which delivers the coded output in simple dependable fashion. A further object is to make the particular code being used a readily changeable one, requiring merely the replacement of one perforated code card by a different code card. Another object is toprovide for shift as between upper and lower case letters.

The keyboard may be used to operate a receiver or more specifically a printer, with multiple conductors extending therebetween. A further object is to provide latch means which holds a key lever depressed, which in turn prevents the operation of any other key lever, until a signal is received back from the receiver or printer indicating that the preceding signal has been received and utilized. Such return signal is momentary, and if such a signal is received while a key is still depressed, the key lever may be relatched, but a further object of the invention is to prevent this contingency by providing means to hold the latch bar in released position until the key lever rises.

The keyboard may be transmitting to a receiver or printer which at times receives signals from one or more other keyboards. In such case the receiver or printer may be arranged to send a signal to prevent operation of all keyboards other than the one already in use, and another object of the present invention is to provide the keyboard with means to lock the same in response to such an external lock signal.

To accomplish the foregoing objects, and other more specific objects which will hereinafter appear, my invention consists in the keyboard elements and their relation one to another as are hereinafter more particularly described in the following specification. The specification is accompanied by drawings in which:

FIG. 1 is a perspective view showing a keyboard embodying features of the invention, the keys and key levers intermediate those near each end being omitted to simplify the drawing;

FIG. 2 is a perspective view at one end of the keyboard, with the cover and key levers removed, and with the code card and its support frame slid partly out of the keyboard;

FIG. 3 is a fragmentary plan view showing collateral conductive wires which underlie the perforated code card;

FIG. 4 is a fragmentary vertical section taken approximately in the plane of the broken line 44 of FIG. 3;

FIG. 5 is a vertical section through the keyboard taken approximately in the plane of the line 55 of FIG. 2 with only the back or fourth row of keys shown;

FIG. 6 is a plan view of a perforated code card mounted in a support frame forming a part of the keyboard, with the support frame removed from the keyboard, and omitting the perforations intermediate those near each end to simplify the drawing;

FIG. 7 is a fragmentary vertical section explanatory of the key lever tensioning means, and is taken approximately in the plane of the line 77 of FIG. 1;

FIG. 8 is a vertical section explanatory of the shift key and shift lock linkage, and is taken approximately in the plane of the line 88 of FIG. 1;

FIG. 8A is explanatory of a part of FIG. 8;

FIG. 9 is a fragmentary plan view looking down at a part of the keyboard corresponding to the corner which is at the top of FIG. 1;

FIG. 10 is a fragmentary plan view looking down at what would correspond to the right hand corner of FIG. 1;

FIG. 11 is a fragmentary vertical view showing the action of the latch bar and lock balls;

FIG. 12 is an end view explanatory of the construction of the cradle;

FIG. 13 is a vertical elevation explanatory of the code card latch and tensioning means;

FIG. 14 is an end view explanatory of the keyboard locking mechanism; and

FIG. 15 is a combined schematic and electrical diagram.

Referring to the drawing, and more particularly to FIG. 1, the keyboard may resemble a standard keyboard, with four rows of keys 12, the keys being mounted at the forward ends of key levers which are pivoted at the rear. The coded output is transmitted on a 'plurality of electrical conductors, and a multiple-pin detachable connector may be provided at 14 for connection to a cable extending to a receiver, which usually is or includes a printer. A conventional spacer bar is shown at 16. Upper and lower case letters may be provided by means of shift keys 18 at both ends of the keyboard, which rock a rod 20, which in turn operates linkage supported at 22 to provide the desired shift. The shift may be locked by means of a shift lock key 24. The key resistance or tension is adjustable by means of a knurled wheel 26. A cover plate 28 at one end of the machine is readily removed to expose a frame carrying a code card which may be slid out of the machine and replaced by another code card providing a different code output, as for a different code or a different language.

Referring now to FIG. 3 the keyboard includes collateral taut conductive wires 30, there being ten such wires in the present case. One end wire, say the wire 34, acts as a common wire. Another wire, in this case the other end wire 32, may be termed a clutch wire, or count wire, it serving to trip the receiver or printer to which the keyboard is connected.

To keep the wires independently taut, they are pulled at their ends by pull springs 36. In order not to unduly increase the size of the keyboard housing, the pull springs are connected after reversely bending the wires around end insulators 38 acting as pulleys. This is best shown in FIGS. 3, 4 and 13 referring to which the wire 30 turns around an insulator 38 and is connected by a link 40 to a pull spring 36.

The left end of pull spring 36 (FIG. 4) is booked through a perforation in a plastic strip 42 which is cemented or riveted to one end of a piece of sheet plastic 44 underlying the taut wires 30. This construction is duplicated at the other end, and the plastic 44 thus serves to insulatedly connect the ten springs at one end to the ten springs at the other end.

Two springs 36, one at each end, could be connected by a strand, or could be connected directly to one another, or a single spring could be used at the middle for each wire, but it is preferred to use the plastic sheet 44 in the manner here shown because it serves a further purpose. It also supports a number of spaced blocks of yieldable insulating material 46 (FIGS. 3 and 4) which are disposed between the taut wires thereabove, and the sheet 44 therebeneath, in order to help support the wires at desired elevation. A foam o1- sponge plastic may be used for the blocks 46.

In FIG. 4 it may be pointed out that the end wire 34 is shown somewhat lower than the wire 30. It is preferred to lower the two end wires 32 and 34 (FIG. 3) slightly, relative to the intermediate eight wires 30. At the left end, not shown, this is done by making the end grooves of somewhat reduced radius, either by deepening the grooves, or by reducing the diameter of the pulley. The purpose is to insure contact with the code wires 30 before there is contact with the common wire and the clutch wire which signals the transmission of a code character. At the right end shown there is an additional insulator 48 which determines the level of the wires, as described later.

Contact with the taut wires is obtained by means of collateral shorting bars which are disposed over the wires and which extend transversely thereof. Such shorting bars are shown at 50 in FIGS. 1, 2, and 15. There is one such shorting bar for each key lever, and each key lever depresses its particular shorting bar. Referring to FIG. 5 the shorting bar 50 is made of metal and is conductive, but it is carried by an insulation support 52 which is pivoted at 54 on an intermediate lever 56, which in turn is moved downward by an adjacent key lever 58 having a pin 60 overlying the intermediate lever 56. Considered more specifically, key lever 58 has a notch at its rear end which engages one edge 62 of an inverted channel 64, thus pivoting the key lever. The intermediate lever 56 is notched at its forward end and engages the upper edge of a fixed pivot wall 66. The lever may be held against disengagement at the pivot by means of a removable retainer plate 68-. The intermediate lever 56 is extended rearwardly far beyond pivot 54 and turns downward at its rear end for latching and locking purposes described later.

It will be understood that the forward ends of the key levers differ in length to provide the four banks of keys, but the rear portion of each key lever, that is the part shown in FIG. 5, is the same for all of the key levers. The forward extensions differ in length, and differ in the height to which they turn upward to carry the key button 12. This is shown in boken lines in FIG. 7 at 70 for the highest bank, 72 for the next lower bank, 74 for the next lower bank, and 76 for the lower bank of keys. Inasmuch as it is desirable that the amount of downward travel of the keys be the same, the location of the pin 60 (FIG. 5) along the key lever may be appropriately varied, and this is indicated in broken lines at 78. Thus the depression of the shorting bar 50 may be made the same for each bank of key levers, while at the same time maintaining like travel of the keys 12.

Referring now to FIGS. 2 and 6, a flexible code card I 80 made of a thin flexible insulating material is disposed between the shorting bars 50 and the conductive wires 30. The code card 80 has perforations 82 best shown in FIG. 6, which are located in registration with crossover points of the shorting bars and the wires. The perforations beneath any one shorting bar are selected in number and in location in accordance with a desired code for the alpha-numeric or other character on the key lever which depresses that particular shorting bar. The shorting bar when depressed by a key, serves to make electrical contact with the wires through the perforations in the code card. The code may be one of the standard 5 or 6 level codes, or Whatever code is desired. In effect, the selected code wires are connected to a common wire 34, and another common wire 32 may be used to trip the printer. This wire may be termed a coun wire or a clutch wire because it releases the clutch to produce the desired print action in a typical motor driven printer.

In practice it is preferred to use double rather than single wires, and this is shown in FIG. 5 in which each of the wires 30, 32 and 34 consists of two wires in immediate side by side relation. This affords greater contact surface for electrical contact with the shorting bar. The wires are of reduced diameter and are more flexible and are easier to handle than would be a single wire of greater diameter.

The full keyboard here shown provides upper and lower case letters. Referring to FIG. 6 the insulating portion of the code card may be folded and cemented at its ends about bars 84 and 270 which are received in a frame having side rails 88-. Referring now to FIG. 5, the code card frame is received in closely fitting guide tracks 90 forming part of a cradle generally designated 92 which may be shifted relative to the wires and shorting bars. It is shiftable fore and aft, as illustrated by the change from the solid line position 92 to the broken line position 92. This shift could be a sliding action, but in the present case it is provided by means of four upright support links 94. The links are mounted at their lower ends on stationary pivots 96, while their upper ends are pivoted on the cradle at 98. The cradle is normally pulled to its forward or lower case position by means of one or more pull springs 100. It is pushed to its rearward or upper case position by means of a push rod 102. There are fixed stops to positively limit the forward and rearward travel of the cradle and card.

The upper ends of the links 94 (FIG. 5) are pivoted to ears 250 (FIG. 12) which are formed integrally with a cross member 252 which extends between front walls 254, 256 at the front of the cradle, and a wall 258 at the back of the cradle. These walls extend for the full length of the cradle. There are two cross members 252 with four ears 250 which are located well inward from the ends of the cradle, as shown by the location of the support links 94 in FIG. 3, and neither they nor the support links 94 (FIG. 5) interfere in any way with the fixed structures near the ends of the cradle for supporting the pulley insulators around which the stationary Wires are tensioned. The rails of the frame which carries the code card are slidably received in the guide spaces indicated at 260 and 262 (FIG. 12) formed in the tracks 90 of the cradle.

The pivots 96 (FIG. 5) are preferably rods, and the support links 94 for the cradle are preferably secured to the rods 96, thus acting as stabilizing rods or parallel motion mechanism to insure equal motion at both ends of the cradle. Suitable stops are provided to positively locate the cradle in its forward and rear positions, so that the perforations of the code card will be in proper registration with the stationary code wires.

Referring now to FIG. 8A the shift key 18 is mounted on a key lever 104 and may be depressed from the solid line position 18, 104 to the broken line position 18', 104' (FIG. 8). The key lever has a pin 106 (FIG. 8A) which is received in a slot 108 formed at the free end of an arm 110 which is secured to the long rod 20 previously referred to in FIG. 1. Depression of the key moves the arm from the solid line position 110 (FIG. 8) to the broken line position 110' thereby turning the rod 20.

As shown in FIG. 1, this linkage and a shift key are provided at both sides of the keyboard, so that shift may be provided with either the left hand or the right hand. At its midpoint the rod 20 carries an arm 112 (FIGS. 1 and 8) which is pivoted at 114 to a pusher link 116. This is supported by the lower end of a support link 22, and at its rear end the pusher link 116 has a sidewardly bent tab 118 which is disposed in front of the push rod 102 previously mentioned. Depression of either shift key 18 moves the push rod 102 rearward, as shown by the change of tab 118 from the solid line position in FIG. 8 to the broken line position 118, thereby moving the cradle bodily rearward as shown in broken lines at 92 in FIG. 5.

When upper case letters are to be used for some time, the shift key may be locked in down position, and for this purpose a shift lock key 24 is provided, it being on a lever 120 (FIG. 8) which has a detent lug 122 so located as to enter a notch 124 in the shift key lever 104 when the latter is in down. position, and serves to lock the same in that position. To release the shift lock the shift key 18 may press downward somewhat further than its locked position, and this releases the shift lock lever 120, which then rises under the spring action provided for all keys.

A main feature of the present keyboard is the ease of changing the code card 80 and thereby changing the code which is being used. It is also useful for changing from one language to another. Referring to FIG. 6 metal end bars like bar 84 are permanently secured to the flexible card 80, as by folding and cementing the plastic around the metal. The side rails 88 are permanently connected by cross rails which are shown at 130 and 86. Bar 84 moves into the position shown, and the card 80 is held taut because the bar 270 at the other end is drawn toward the right. In the present frame the desired pull is provided by two torsion springs 132 acting through appropriate connections. An angle piece or handle 134 facilitates movement of the frame into or out of the keyboard. When it is moved into the keyboard it is locked in correct position by means of a suitable latch 136 controlled by a handle 138 and normally pulled into locking position by means of pull spring 140. The latch engages a fixed part 137 of the cradle.

The latch and the mechanism for tensioning the code card may be described further with reference to FIG. 13, in which it will be seen that the code card 80 is cemented about bar 270 which has notches which are anchored on side arms 272 which are urged rearwardly by torsion springs 132. The other ends of the torsion springs are anchored in the upturned part 274 of a plate 276 which supports the code card against upward movement. The arms 272 may be connected by a strip 278, which may be formed integrally with the arms 272.

FIG. 13 further shows the latch member 136 which holds the card frame against outward movement until the latch is released by depressing the handle 138. Spring 140 locks the latch member against detent 137.

FIG. 13 also shows how the insulating pulleys 38 at the right side of the keyboard are supplemented by a small diameter insulating cylinder (r pulleys) 48, the latter being located at the precise height wanted for the code wires. This double support is not needed at the left side of th keyboard, and is used at the right side merely to lower the main pulleys 38 somewhat for greater clearance when inserting or removing the code card and its frame. At the left side the main pulleys are of correct height, and the same can be done at the right side if so desired.

Referring to FIG. 5, it will be recalled that the side rails 88 are accurately located in guide tracks or channels 90 forming a part of the cradle 92. FIG. 2 shows the frame and code card pulled part way out of the keyboard. The frame may be pulled all the way out of the keyboard and the card replaced by another card. Each code card could be permanently mounted in its own frame, but preferably the code card and its end bars are removably mounted in a single frame. It is essential that the code card be properly located relative to the shorting bars, and the lock mecha nism 136, 137 serves this purpose. After a code card and frame have been inserted in the machine the opening at the side may be covered by the cover plate shown at 28 in FIG. 1, this being held in position by three quick detachable fasteners 142.

The latch mechanism to hold a shorting bar down until the receipt of the code signal is acknowledged by the printer may be described with reference to FIGS. 5, 10 and 11 of the drawing. Each intermediate lever 56 extends downward at its rear end, as shown at 144. This part moves down to the broken line position 144' (FIG. against a leaf spring 146 which then is bent down to the broken line position 1 46'. Spring 146 is one of a series of springs, there being one for each intermediate lever, and the springs may all be formed out of a single strip of material by slitting the material to form the individual springs. At their lower or fixed ends they remain integral with the strip, and the latter may be secured directly against the base 148 of the keyboard by means of an overlying strip shown at 147 in FIG. 10.

Referring now to FIG. 11, the depending portion 144 of intermediate lever 56 is latched in downward position by means of a long latch bar 150 which extends across the keyboard and serves to latch any one of the intermediate levers. Reverting now to FIG. 5, the ends of the latch bar 150 are carried at the lower ends of two support arms 152 which depend from pivots 154, and the upper ends 156 of which are pulled rearward by pull springs 158, thus urging the latch bar 150 forward in looking direction. Arms 152 could be secured to a rod at 154 so that release movement of one arm causes release movement of the other at the opposite side of the keyboard, or alternatively, the bar 150 may be rigidly secured to both arms, which is the case here.

The latch bar 150 is released or pulled rearwardly by means of a solenoid 160 (FIGS. 2 and 5). The solenoid core 162 is connected by means of a short link 164 to the arm 152 at one end, in this case the right end of the keyboard. Solenoid 160 is energized in response to a return signal or acknowledgement signal received by the keyboard from the printer or other electrical receiving unit to which the signal has been sent. Thus even if a key is depressed and immediately released, its shorting bar is held down until the signal has been acknowledged from the other end of the line.

The opposite difliculty may arise, that is, a key may be held depressed unduly long. Inasmuch as the release pulse from the printer is only momentary, the latch bar 150 in such case might again lock the intermediate lever. To prevent this a series of detents 166 (FIGS. 5 and 10) is provided. These are pivoted at 168, and overlie the latch bar 150. Any one of them may engage and hold the latch bar in rearward or released position as long as the intermediate lever is down. Each intermediate lever has a short pin or lug 170 which is disposed beneath the free end of its adjacent detent 166, as shown in FIG. 5, and when pin 170 rises it releases the detent andso would permit forward movement of the latch bar 150. At first the part 172 (FIG. 11) of the intermediate lever comes in front of the latch bar 150, thus holding the latch bar back until part 172 rises all the way. The lower end portion 174 (FIG. 11) is cut away enough to permit for ward movement of the latch bar, as will be seen in FIG. 5. Consequently on downward movement of one intermediate lever, the latch bar is free to move forward without interference by the remaining intermediate levers, all of which are in raised position. Also one detent 166 is lowered, while the others remain up.

The operation of one key lever prevents the operation of any other key lever until the first is released, and for this purpose a ball lock system is provided. Referring to FIGS. 5, 9 and 10, a channel member 176 carries a row of steel balls 178. The channel member 176 is vertically slotted to afford downward movement of the intermediate levers. Referring to FIG. 11, the depending part 144 is cut away to provide an edge 180 which is located between two balls 178. The balls are so spaced as to accommodate downward movement of only one of the parts 180 between any two of the balls. This takes up the small amount of clearance that is provided, thus preventing the downward movement of any other of the parts 180. No second key can be operated while a first key is still down, and even if the first key is released, but if for some reason its intermediate lever remains latched in down position, as by means of the latch bar previously described, the second key cannot be operated.

The keyboard is further provided with means to lock it against operation when so signalled from the receiver or printer. In a typical case a single printer may be connected to a number of keyboards located at different places, and it is desirable to lock all but one keyboard against use when one keyboard is already in operation. Referring to FIG. 9, a lock solenoid 182 is energized in response to a remote signal. The solenoid operates a plunger 184 which is connected to a blade 186 having the same thickness as one of the intermediate levers. It is aligned alongside one of the balls 178, and when the solenoid is energized, the blade 186 is advanced between the ball and a fixed end 179, thus taking up the small available clearance, and preventing operation of the keyboard. (The blade could be moved between two balls.)

The mechanism may be described in greater detail with reference to FIG. 14 of the drawing, which shows the ball 178 in slotted channel 176, and the blade 186 which is moved forward between an end wall and a ball. This blade is formed integrally with an arm 282 the lower end of which is pivoted at 284. The arm is urged rearwardly by means of a torsion spring 286. Solenoid 182 is a push solenoid, and its plunger 184 bears against an arm 246 the upper end of which is pivoted at 288. The lower end 290 bears against the arm 282, and moves the blade 186 from the solid line position to the broken line position 186' alongside a ball 178. This linkage is not essential, but is convenient in order to multiply the mo tion of the solenoid, keeping in mind that the latter preferably is operated by a relatively low voltage.

The resistance to movement or tension of the keys may be adjusted to suit the preference of the operator. The mechanism for this purpose may be described with reference to FIG. 7 of the drawing. The key levers normally are raised by leaf springs 200. There is one spring for each key lever, and they may be individual, but usually they are formed by slitting a single piece of resilient material, the lower ends being integral at a base portion 202. This is clamped between parts 204 which are secured at each side of the keyboard to a pivot 206. An arm 208 is secured to one end pivot 206, and is connected at 210 to the rear end of a link 212, the forward end of which is bent sideward and is pivoted at 214 in a yoke 216 formed at the rear end of a screw 218. The axial position of the screw may be varied by rotating the knurled adjustment wheel 26 previously referred to in connection with FIG. 1, the wheel 26 being internally threaded to mate with the screw 128. It will be evident that rotation of wheel 26 to pull the screw forward raises the springs and increases the spring force against the levers, while opposite movement lowers the springs and reduces the key tension.

In the event of power failure the solenoid 160 would not be energized to release the depressed shorting bar. If in such case someone were to attempt to remove the code card he might damage the code card and/or the depressed shorting bar. Referring to FIG. 1, he would first remove the access door 28, and this door is provided with means to insure release of the shorting bar. Referring to FIG. 10 the door 28 carries a pin 220 which bears against an angle lever 222, 224. This lever is pulled by a spring 226 but is normally held by pin 220 in the inoperative position shown. However, when the access door 28 with its pin 220 is removed, spring 26 pulls lever 224 against the arm 152 which carries the latch bar 150, and moves it rearward as though solenoid 160 had been energized. Thus the intermediate lever and its shorting bar are released as the access door 28 is being removed.

A combined electrical and schematic diagram is given in FIG. 15, referring to which key lever 58 depresses intermediate lever 56 which depresses insulating holder 52 and metal shorting bar against the flexible code card 80, thereby contacting conductors 30 through perforations. The common wire 34, the code conductors 30, and the count or clutch wire 32 are all connected to conductors forming part of a multiwire cable 230. There is an additional conductor 232 which may be connected by means of a switch 234 and wire 236 to the common wire 34. The switch 234 is operated by a key on the keyboard marked Repeat, and causes repeat printing at the remote printer.

The latch release solenoid 160 is controlled by a conductor 238, and the keyboard locking solenoid 182 is controlled by a conductor 240, these solenoids having a common return wire 242, so that three wires extend to the remote receiver electronic circuitry and/or printer. The common wire 242 is separated from the common wire 34 because a difference in operating voltage may be desired. The cable 244 may be combined with the cable 230, instead of being separate as shown.

In the present case the card has fourteen horizontal rows of perforations (FIG. 6), corresponding to seven code wires. The number is doubled because of the shift as between upper and lower case letters. Perforations are not needed for the two end wires which are always contacted, and in relation to FIG. 6 these end wires are located beyond the edges of the card 80, as will be seen also in FIG. 5 where the card, which is shown in section, does not overlie the end wires 32 and 34. The count wire or clutch wire initiates the cycle, whether print or space or special function. Six code wires take care of a six level code, and the seventh code wire may be used to take care of an additional information bit in the event that more than six bits are wanted. It may be referred to as a parity wire. In FIG. 6 the lower edge of the card has spare room in which perforations may be provided for this seventh or parity wire.

The card may be made of full width, if desired, with two additional lines of perforations near each edge, for the common wire and for the clutch wire.

The card 80 is preferably made of Mylar, but other materials may be used, for example nylon, Teflon, or Delrin. The card is only 0.003 inch thick.

The shorting bar may be made of beryllium copper, and it is preferably plated with copper and then nickel and then gold for good electrical contact. The holder for the shorting bar is made of Delrin, which is an acetal thermoplastic manufactured by Du Pont.

It is believed that the construction and operation of our improved keyboard, as -well as the advantages thereof, will be apparent from the foregoing detailed description.

We claim:

1. A keyboard for providing a coded output, comprising collateral taut conductive wires, collateral shorting bars disposed over the wires and extending transversely thereof, a flexible code card made of insulating material and disposed between the shorting bars and the wires, and key levers for selectively depressing one shorting bar or another, said code card having perforations in registration with cross over points of the shorting bars and the wires, said perforations beneath any one shorting bar being located in accordance with a desired code to correspond to the character on the key lever which depresses that particular shorting bar, said shorting bar when depressed by a key serving to make electrical contact with the desired wires through the perforations in the code card.

2. A keyboard as defined in claim 1, in which the code card is so mounted therein as to be changeable in order to change the code of the coded output of the keyboard.

3. A keyboard as defined in claim 2, in which the code card is mounted in a cradle which may be shifted relative to the wires and shorting bars, and in which there is a shift key and linkage whereby the shift key shifts the position of the cradle in order to use different perforations in the card, usually to provide upper or lower case letters.

4. A keyboard as defined in claim 3, in which there is a latch bar to hold down a shorting bar that has been depressed, and a solenoid connected to the latch bar for releasing the same in response to a return signal received by the keyboard.

5. A keyboard as defined in claim 4, in which there is a detent for engaging and holding the latch bar when released by the solenoid, and a detent release means which releases the detent when a shorting bar rises.

6. A keyboard as defined in claim 5, in which there is a channel nearly but not quite fully occupied by a row of balls, and in which linkage associated with each shorting bar moves between two adjacent balls when a key is depressed, the balls then being in contact to prevent the depression of any other shorting bar until the first shorting bar is raised.

7. A keyboard as defined in claim 6, in which there is a solenoid and a blade actuated thereby to be moved into a position adjacent one of the balls, to thereby prevent the operation of the keyboard when the solenoid is energized in response to an outside signal.

8. A keyboard as defined in claim 7, in which the collateral wires pass around a round insulator at each side of the keyboard, and in which the reversely bent lower ends of the wire are tensioned by means of pull springs to keep the wires taut independently.

9. A keyboard as defined in claim 8, in which the pull springs at the ends of the wires are connected to the ends of a piece of sheet plastic underlying and spaced downward somewhat from the wires, and in which there are blocks of yieldable insulating material disposed between the wires and the plastic sheet in order to help support the wires at desired elevation.

10. A keyboard as defined in claim 9, in which the wires include a common wire, and a clutch wire, and in which the insulators are grooved to locate the wires against sideward movement, thereby maintaining the desired spacing therebetween, and in which the groove for the common wire and the groove for the clutch wire are of somewhat reduced radius in order to insure contact by the shorting bar against the other code wires before the shorting bar contacts the common wire and clutch wire.

11. A keyboard as defined in claim 1, in which the code card is mounted in a cradle which may be shifted relative to the wires and shorting bars, and in which there is a shift key and linkage whereby the shift key shifts the position of th cradle in order to use different perforations in the card, usually to provide upper or lower case letters.

12. A keyboard as defined in claim 1, in which there is a latch bar to hold down a shorting bar that has been depressed, and a solenoid connected to the latch bar for releasing the same in response to a return signal received by the keyboard.

13. A keyboard as defined in claim 12, in which there is a detent for engaging and holding the latch bar when released by the solenoid, and a detent release means which releases the detent when a shorting bar rises.

14. A keyboard as defined in claim 1, in which there is a channel nearly but not quite fully occupied by a row of balls, and in which linkage associated with each shorting bar moves between two adjacent balls when a key is depressed, the balls then being in contact to prevent the depression of any other shorting bar until the first shorting bar is raised.

15. A keyboard as defined in claim 14 in which there is a solenoid and a wedge actuated thereby to be moved into a position between two of the balls, to thereby prevent the operation of the keyboard when the solenoid is energized in response to an outside signal.

16. A keyboard as defined in claim 1, in which the collateral wires pass around a round insulator at each side of the keyboard, and in which the reversely bent lower ends of the wire are tensioned by means of pull springs to keep the wires taut independently.

17. A keyboard as defined in claim 16, in which the pull springs at the ends of the wires are connected to the ends of a piece of sheet plastic underlying and spaced downward somewhat from the wires, and in which there are blocks of yieldable insulating material disposed between the wires and the plastic sheet in order to help support the wires at desired elevation.

18. A keyboard as defined in claim 16, in which the wires include a common wire, and a clutch wire, and in which the insulators are grooved to locate the wires against sideward movement, thereby maintaining the desired spacing therebetween, and in which the groove for the common wire and the groove for the clutch wire are of somewhat reduced radius in order to insure contact by the shorting bar against the other Wires before the shorting bar contacts the common wire and clutch wire.

References Cited UNITED STATES PATENTS 1,060,939 5/1913 Potts. 1,944,586 1/1934 Woodward. 2,049,705 8/1936 Lemmon. 3,066,863 12/1962 Wilson.

THOMAS A. ROBINSON, Primary Examiner.

U.S. Cl. X.R. 

1. A KEYBOARD FOR PROVIDING A CODED OUTPUT, COMPRISING COLLATERAL TAUT CONDUCTIVE WIRES, COLLATERAL SHORTING BARS DISPOSED OVER THE WIRES AND EXTENDING TRANSVERSELY THEREOF, A FLEXIBLE CODE CARD MADE OF INSULATING MATERIAL AND DISPOSED BETWEEN THE SHORTING BARS AND THE WIRES, AND KEY LEVERS FOR SELECTIVELY DEPRESSING ONE SHORTING BAR OR ANOTHER, SAID CODE CARD HAVING PERFORATIONS IN REGISTRATION WITH CROSS OVER POINTS OF THE SHORTING BARS AND THE WIRES, SAID PERFORATIONS BENEATH ANY ONE SHORTING BAR 